This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. We achieved the following research goals: + Using the second MJ4-based system that we developed in the previous funding period we directly cloned a pilot panel of subtype C env genes that were generated in collaboration with Dr. Eric Hunter using a Single-Genome Amplication (SGA) protocol. + After completing the construction of 40 subtype C HIV molecular clones representing the viral variants from 3 matched Donor/Recipient couples from Dr. Susan Allen's Zambian discordant couple cohort and performing replication assays on the subtype C HIV molecular clones on primary CD4 T cells, we have now analyzed the he replication kinetics of each molecular clone by calculating the Area Under the Curve (AUC) to define the replication phenotype. + Applied the Lac-regulatable dual expression adenovirus vector system that we developed during the previous budget periods to a new vaccine project where we are investigating the immunogenicity of the recently discovered gammaretrovirus, xenotropic murine leukemia-related virus (XMRV). Significance: Provides unique and valuable reagents, key to understanding the phenotype associated with HIV-1 transmission and the targets for an effective vaccine against HIV-1 infection.